Hi there!
Thanks for contacting us.
From Pro version to lite is not recommended. It can cause issues.
Your subscription is a one-time payment. You will not need to renew later to keep using end-products. But if you need updates, support, and download access after the expiration, then you need to renew the subscription.
So it is lifetime in terms of usage. If you have downloaded the product and kept it on your machine, then you can use it even after the expiration of your subscription.
You will get information on what happens when subscription runs out in the pricing page too:
https://www.joomshaper.com/pricing#v-pills-general
Best Regards